原位自生钛基复合材料最佳铣削温度区间的研究

Research on Optimum Cutting Temperature Range for Milling in Situ Titanium Matrix Composite

为实现钛基复合材料的高效、低损伤铣削加工及降低该材料的铣削加工成本,对其最佳铣削温度区间进行研究。采用聚晶金刚石(PCD)刀具,研究切削温度对铣削该复合材料时的刀具寿命、刀具磨损和加工表面质量的影响规律。试验结果表明:PCD刀具的最佳铣削温度区间为500℃-600℃,考虑切削过程中刀具磨损对切削温度的影响,PCD刀具铣削钛基复合材料时的最佳初始切削温度区间为420℃-480℃;PCD刀具在最佳铣削温度区间切削时,刀具崩刃和磨粒磨损显著减轻,且适当提高切削速度并减小进给量可进一步延长刀具寿命;在高于最佳铣削温度下切削时,刀具扩散磨损剧烈,且加工表面变质层深度显著增大。研究得出以下结论:PCD刀具高速铣削钛基复合材料时存在最佳铣削温度区间和最佳初始切削温度区间,在最佳铣削温度下切削有利于增强相被刀具原位压入基体或随基体一起协同变形发生转动,从而明显减少加工表面的划痕、微坑洞、撕裂等缺陷。

In order to realize high efficiency and low damage milling of Ti matrix composites and reduce the machi- ning cost, the optimum cutting temperature range was studied. PCD tools were used to investigate the tool life, tool wear and machined surface integrity at different cutting temperature ranges. The results showed that the optimum cutting temperature range for PCD tool was 500 -600℃ when milling vol. 10% （TiCp ＋ TiBw ）/TC4 composite. By considering the effect of tool wear on the cutting temperature, the optimum initial cutting temperature range was 420 -480℃. Cutting at the optimum cutting temperature, tool edge chipping and abrasive wear were greatly alleviated, and hence tool life was significantly improved. Besides, increasing the cutting speed and reducing the feed rate can further increase the tool life. When cutting at a temperature higher than the optimum cutting temperature, severer diffusive wear presented on the tool face and deeper deformation layer was found on the machined surface. When cutting at the optimum cutting temperature, the reinforcement was more easily to be in situ pressed into the matrix or took place co-deformation with the Ti matrix. Accordingly, the defects of grooves, micro pits and matrix tearing were greatly reduced. It is concluded that there is an optimum cutting temperature range when milling Ti matrix composite with PCD tool. When cutting at the optimum cutting temperature, tool life can be greatly increased and the surface quality also can be significantly improved simuhaneously.